Load lifting mechanism



N. E. SHUEY LOAD LIFTING MECHANISM Filed Oct. 15, 1965 Neil E. Shun-3 INVENTOR United States Patent 3,310,335 LOAD LIFTING MECHANISM Neil E. Shuey, 7206 N. Interstate Ave., Portland, Oreg. 97217 Filed Oct. 13, 1965, Ser. No. 495,544 6 Claims. (Cl. 29488) This invention relates to devices for lifting loads, and more particularly to load lifting mechanism which includes a self-contained power source for operating the load engaging elements of the mechanism, and which also preferably includes means for controlling said operation from a location remote from the mechanism.

In load lifting devices such as logging tongs which serve to grasp a log for elevation and transport to an unloading site, it has been a requirement heretofore that an external source of power he provided for operating the tongs. Such external source may be electric lines supplying electric power to a drive motor on the logging tongs unit, or hydraulic or other fluid pressure lines supplying a fluid pressure motor on the logging tongs unit.

Furthermore, it is the usual requirement with such devices of the prior art that an additional control line be provided for actuating the power unit to release the log from the tongs at the unloading site.

The electric or fluid pressure lines and the control line must be extensible with the hoisting cable which supports the logging tongs unit, as well as movable therewith over the operating range of the unit. Not only is the requirement for such lines and the maintenance and repair thereof a considerable expense, but their presence with the hoisting cable constitutes an objectionable nuisance and hazard.

It is the principal object of the present invention to provide load lifting mechanism of the class described which includes a self-contained power source for operating the load engaging elements of the mechanism, thereby eliminating the former requirement of undesirable power supply lines.

Another important object of this invention is the provision of load lifting mechanism of the class described in which a self-contained power source for the load engaging elements is controlled from a location remote from the mechanism by means of the transmission of a high frequency electric signal, thereby eliminating the former requirement of an undesirable control line.

A further important object of the present invention is the provision of load lifting mechanism of the class described which is of simplified construction for economical manufacture.

The foregoing and other objects and advantages of this invention will appear from the following detailed description, taken in connection with the accompanying drawing in which the single figure is a vertical sectional view of load lifting mechanism embodying the features of the present invention.

The load lifting mechanism of the present invention is illustrated in the drawing as a logging tongs device in which a pair of log engaging tong elements 10, 12 are supported upon a housing 14 for movement relative to the housing and each other. In the embodiment illus' trated, both tong elements are supported on pivot pins 16 for pivotal movement relative to each other and to the housing. The link member 18 pivotally interconnects the pair of tong elements, as by means of the pivot pins 20, on opposite sides of their mounting pivots 16, to effect simultaneous pivotal movement of the tong elements either in closing direction or in opening direction.

A reversible fluid pressure drive unit interconnects the housing and the link member, for effecting movement of the log tongs. In the embodiment illustrated, the drive unit comprises a reversibly extensible piston and cylinder unit. One end of the cylinder 22 is mounted pivotally on the housing, as by means of the pivot pin 24, and the piston rod 26 extending from the piston 28 through the opposite end of the cylinder is connected pivotally to the link member, by means of the pivot pin 30.

The load lifting mechanism of the present invention is provided with a self-contained power source for the drive unit. Thus, in the embodiment illustrated, there is supported within the housing a high pressure fluid supply container 32 and a lower pressure fluid supply container 34. These containers may serve to confine only air or other gas under pressure as the source of fluid power. However, it is preferred that they be of the conventional accumulator type wherein each container is filled partially with hydraulic liquid and is then pressurized with air or other gas, admitted through the valve element 36 which is exposed through the opening 38 in the housing.

The high pressure container 32 is connected through the conduit 40, and preferably through the check valve 42, to one port of a conventional four-way adjustable control valve 44. The lower pressure container 34 is connected through the conduit 46 to a second port of the control valve. A third port of the control valve is connected through the conduit 48 to one end of the drive cylinder 22, and a fourth port in the valve is connected through the conduit 50 to the opposite end of the cylinder.

Thus, in one position of adjustment of the valve, high pressure fluid is delivered from the container 32 through the check valve 42, control valve 44 and conduit 48 to the left hand end of the cylinder, causing the piston 28 to be moved toward the right to extend the piston rod and draw the logging tongs together. Fluid pressure on the opposite side of the piston is communicated back through the conduits50 and 46 to the lower pressure container 34.

In a second position of adjustment of the control valve, high pressure fluid is delivered from the container 32 through the check valve 42, control valve 44 and the conduit 50 to the right hand end of the cylinder 22, causing the piston 28 to move toward the left and retract its piston rod, thereby pivoting the log tongs outward to release their engagement of a log. Fluid pressure on the left side of the piston is communicated back through the conduits 48 and 46 to the lower pressure container 34.

Means also is provided for replenishing the fluid pressure in the high pressure container 32 after each successive operation of the drive unit. In the embodiment illustrated, this means is provided by the fluid pressure pump which includes the cylinder 52 having therein a piston 54 reciprocative in retracting and pumping direction. A piston rod 56 is connected to the piston and extends outwardly through the cylinder.

The cylinder is secured to the housing 14, and the projecting end of the piston rod abuts against the plate 58. A plurality of support rods 60 project from this plate freely outward through openings in the housing for reciprocative movement relative to the housing, such movement being guided by the surrounding skirt portion 62 of the housing. The outwardly projecting ends of the rods secure a connecting head 64, as by means of the nuts 66. This head is provided with an eyelet 68, or other suitable form of connector, for connecting the free end of a hoisting cable 70 which may extend from a crane, donkey line, or other suitable means.

It will be apparent that the aforementioned manner of mounting the pump may be reversed, if desired. Thus,

the pump cylinder 52 may be mounted in engagement with the plate 58, rather than in engagement with the housing, and the piston rod 56 extended upward into engagement with the housing, rather than into engage ment with the plate.

In either manner of mounting, the pumping end of the cylinder 52, i.e., the end toward which the piston 54 moves in its pumping direction, is connected through the conduit 72 and the check valve 74 to the outlet end of the lower pressure container 34, and through the conduit 72 and check valve 76 to the outlet end of the high pressure container 32.

The check valve 74 is arranged to permit the flow of fluid pressure from the lower pressure container 34 into the cylinder 52, but to prevent the reverse flow back to the lower pressure container. The check valve 76 is arranged to permit the flow of fluid pressure from the cylinder 52 to the high pressure container 32, but to prevent the reverse flow back to the cylinder.

If desired, a relief valve 78 may interconnect the outlet ends of the high and lower pressure containers for the purpose of relieving excessive pressure build up in the high pressure container, by conducting such excess pressure to the lower pressure container.

Means also is provided in the present invention for adjusting the control valve 44 to the alternate positions previously described. In the embodiment illustrated, such means comprises an electrical solenoid 80 the armature 82 of which engages the valve 44 and the coil of which is connected to the battery source 84 of electric power through the control switch 86. This switch may be operated manually, as by a line extending to the location of an operator. However, in the preferred embodiment illustrated, the switch is operable by a relay coil 88 which is connected for actuation by a radio or other high frequency receiver 90 upon activation of the latter by the reception at its antenna 92 of a high frequency electric signal transmitted from a remotely located transmitter (not shown). The receiver and transmitter combination may be of any desired and well known construction, with the receiver being mounted in the housing and the transmitter located at the operators station, or carried in the hand of an operator on the ground.

The operation of the load lifting mechanism described hereinbefore is as follows: Preliminary to use, the high and lower pressure fluid supply containers 32 and 34 are pressurized with air or other gas to desired magnitudes, for example 200 p.s.i. and 75 psi, respectively. With the radio receiver 90 inactivated, the control switch 86 is in the normally open position illustrated and the solenoid 80 is deenergized. The control valve 44 thus is in the position of adjustment communicating the high pressure container 32 with the left hand end of the cylinder 22, and the right hand end of the cylinder in communication with the lower pressure container 34. Thus, the piston 28 is forced toward the right, as illustrated, and the logging tongs 10, 12 are pivoted to their closed positions.

Let it now be assumed that the load lifting mechanism is elevated by the hoisting cable 70 to a suspended position above a log L to be transported to another site. The operator then activates the transmitter to send a signal to the receiver 90. The receiver thus is activated, energizing the relay coil 88 and closing the control switch 86, completing the electric circuit of the solenoid 80. The valve 44 thereupon is moved to the alternate position of adjustment, communicating the high pressure container 32 with the right hand end of the cylinder 22 through conduit 50 and the left hand end of the cylinder with the low pressure container 34. The piston thus is moved toward the left, simultaneously opening the logging tong elements.

With the log tong elements opened, the operator then lowers the mechanism over the log and then deactivates the transmitter. With consequent deactivation of the receiver and the relay coil, the control switch 86 opens to deenergize the solenoid and return the valve 44 to its initial position of adjustment wherein the high pressure container 32 communicates with the left hand end of the cylinder 22 and the right hand end of the cylinder 8 communicates with the low pressure container 34. The piston 28 thus again moves toward the right to close the log tong elements about the log.

The operator then causes the hoisting cable 70 to be elevated to lift the log from the ground.

As the log is lifted from the ground, its weight causes the housing 14 to move downward relative to the assembly of plate 58, rods 60 and head 64. Thus, the piston 54 in the fluid pressure pump is caused to move in the pumping direction, forcing fluid under pressure from the cylinder 52, through the conduit 72 and check valve 76 into the high pressure container 32. In this manner the weight of the log functions to operate the fluid pressure pump to replenish the fluid pressure previously used from the high pressure container 32 in driving the piston 28 to open and close the log tong elements.

When the log has been transported to the unloading site, the operator again activates the transmitter to send a high frequency signal to the receiver and, consequently, to open the log tongs and release the log. Having thus relieved the tongs of the weight of the log, fluid pressure from the lower pressure container 34 is delivered through the check valve 74 and conduit 72 to the pump cylinder 52. In the absence of the weight of the log, this magnitude of fluid pressure is suflicient to cause the pump piston 54 to retract to the position illustrated, drawing the housing 14 upward relative to the assembly of plate 58, rods 60 and head 64, to the re-cocked position illustrated.

Having released the log from between the tongs, the operator then deactivates the transmitter to return the tongs to the closed position. The assembly now is in readiness for repeating the cycle described above.

It is to be noted in the foregoing illustration that the piston 28 operated four times in the cycle whereas piston 54 operated only once in the same cycle. Accordingly, the latter must be capable of displacing at least four times the volume of fluid displaced by one stroke of piston 28.

From the foregoing it will be apparent that the high pressure container 32 serves to supply high pressure fluid to the drive unit 22, 28 to open and close the tongs; that the fluid pressure pump 52, 54 is operated by the weight of the log to pump fluid under pressure to high pressure container 32 to replace the pressure used in operating the drive unit; that the lower pressure container 34- serves to supply fluid pressure to the pump unit to retract the piston 54 to the re-cocked position in readiness for a subsequent pumping cycle; and that the fluid pressure used from the lower pressure container 34 in retracting the pump piston 54 is replenished by fluid pressure returned thereto from the exhaust side of the drive unit cylinder 22.

Thus, the power unit is completely self-contained within the housing 14 of the load lifting mechanism and requires no external power supply lines. Accordingly, in the case of a logging tongs device as illustrated, the only line required for operation of the device is the single hoisting cable 70.

It will be apparent to those skilled in the art that various changes may be made in the size, shape, type and arrangement of parts described hereinbefore .without departing from the spirit of this invention and the scope of the appended claims.

Having now described my invention and the manner in which it may be used, what I claim as new and desire to secure by Letters Patent is:

1. Load lifting mechanism, comprising (a) a housing supporting movable load engaging means,

(b) reversible fluid pressure drive means interconnecting the housing and load engaging means for moving the latter,

(0) a high pressure fluid supply container on the housing,

(d) a lower pressure fluid supply container on the housing,

(e) adjustable valve means connecting the high and lower pressure fluid supply containers to the drive means for operating the latter selectively in said reversible directions,

(f) operator means engaging the adjustable valve means for adjusting the latter,

(g) fluid pressure pump means including a fluid pressure cylinder having therein a piston reciprocative in retracting and pumping directions, the piston having a piston rod extending outwardly through the cylinder,

(h) one of the cylinder and piston rod components of the pump means engaging the housing and the other of said components being movable relative to the housing and adapted for connection to load lifting means,

(i) valve means communicating the lower pressure container with the pumping end of the pump cylinder for passage of fluid only in the direction to said cylinder, and

(j) valve means communicating the pumping end of the pump cylinder with the high pressure container for passage of fluid pressure only in the direction to said container,

(k) the pump means being operable under the Weight of a load being lifted to pump fluid under pressure to the high pressure container, and

(l) the lower pressure container being operable upon release of the weight of a load from the load engaging means to move the pump piston in said retracting direction.

2. The load lifting mechanism of claim 1 wherein (a) the load engaging means comprises a pair of log tongs at least one of which is supported pivotally on the housing,

(b) the drive means comprises a reversible extensible piston and cylinder unit pivotally interconnecting the housing and the pivoted log tong, and

(c) the adjustable valve means connects the high pressure container selectively to one of the opposite ends of the cylinder and the lower pressure container selectively to the other end of the cylinder.

3. The load lifting mechanism of claim 1 wherein the fluid pressure supply containers are adapted to be partially filled with hydraulic liquid and pressurized with a gas.

4. The load lifting mechanism of claim 51 wherein the operator means comprises an electric valve operator on the housing operable from a location remote from the load lifting mechanism.

5. The load lifting mechanism of claim ll wherein the operator means comprises (a) an electric solenoid on the housing,

(b) a source of electric power on the housing,

(c) switch means on the housing releasably interconnecting the solenoid and power source, and

(d) switch actuator means on the housing.

6. The load lifting mechanism of claim 5 wherein the switch actuator means comprises a relay coil connected for operation by a high frequency receiver on the housing upon activation of the receiver by a high frequency electric signal transmitted from a location remote from the load lifting mechanism.

References Cited by the Examiner UNITED STATES PATENTS 3,260,546 7/1966 Stack 29438 X FOREIGN PATENTS 625,847 1/ 1963 Belgium.

GERALD M. FORLENZA, Primary Examiner. G. F. ABRAHAM, Assistant Examiner, 

1. LOAD LIFTING MECHANISM, COMPRISING (A) A HOUSING SUPPORTING MOVABLE LOAD ENGAGING MEANS, (B) REVERSIBLE FLUID PRESSURE DRIVE MEANS INTERCONNECTING THE HOUSING AND LOAD ENGAGING MEANS FOR MOVING THE LATTER, (C) A HIGH PRESSURE FLUID SUPPLY CONTAINER ON THE HOUSING, (D) A LOWER PRESSURE FLUID SUPPLY CONTAINER ON THE HOUSING, (E) ADJUSTABLE VALVE MEANS CONNECTING THE HIGH AND LOWER PRESSURE FLUID SUPPLY CONTAINERS TO THE DRIVE MEANS FOR OPERATING THE LATTER SELECTIVELY IN SAID REVERSIBLE DIRECTIONS, (F) OPERATOR MEANS ENGAGING THE ADJUSTABLE VALVE MEANS FOR ADJUSTING THE LATTER, (G) FLUID PRESSURE PUMP MEANS INCLUDING A FLUID PRESSURE CYLINDER HAVING THEREIN A PISTON RECIPROCATIVE IN RETRACTING AND PUMPING DIRECTIONS, THE PISTON HAVING A PISTON ROD EXTENDING OUTWARDLY THROUGH THE CYLINDER, (H) ONE OF THE CYLINDER AND PISTON ROD COMPONENTS OF THE PUMP MEANS ENGAGING THE HOUSING AND THE OTHER OF SAID COMPONENTS BEING MOVABLE RELATIVE TO THE HOUSING AND ADAPTED FOR CONNECTION TO LOAD LIFTING MEANS, 